These days, electrosurgery is used in many medical fields. In the process, a relatively high voltage, which is applied to a monopolar or bipolar electrode, is used to damage or cut biological tissue in a targeted manner. In order to produce these voltages, use is usually made of an electrosurgical generator (RF surgical generator).
Different types of modulation are used for cutting and/or coagulating the biological tissue. To this end, e.g. bursts must have a quick beginning and end.
EP 1 776 929 A1 describes an electrosurgical generator in which the output voltage of the RF surgical generator can quickly be reduced. In the process, if a threshold is exceeded, the output voltage of the RF surgical generator is quickly reduced by virtue of converting the energy from the power supply unit into heat by connecting an additional load component. A disadvantage of this is that the generated heat needs to be dissipated and that the RF surgical generator is technically complex and has poor cutting properties.
DE 102 18 895 A1 describes a further electrosurgical generator, wherein the output voltage of the electrosurgical generator can quickly be reduced. Here, the output voltage of the power supply unit is reduced by virtue of feeding the output capacitor energy back to the DC voltage supply. As a result, the energy stores on the output side of the DC voltage supply and in the power oscillator are quickly discharged. As a result of this, the output voltage of the electrosurgical generator is quickly reduced. A disadvantage of this is that the electrosurgical generator offers poor cutting properties and the circuit is complicated and technically complex.
US 2004/0193148 A1 describes an electrosurgical generator in which surges in the output voltage of the RF surgical generator can quickly be regulated down. In this case, the resonant frequency of the oscillator is modified by the addition of further components as soon as the output voltage of the RF surgical generator lies above a limit voltage. As a result, the unchanging excitation frequency no longer corresponds to the resonant frequency of the oscillator, as a result of which the output voltage of the RF surgical generator is reduced below the limit voltage, i.e. to the level of a normal output voltage, and sparking is prevented. It is disadvantageous in this case that the circuit is technically complex and sparking, which is advantageous for cutting, is prevented and hence the RF surgical generator offers poor cutting properties.